Some heating, ventilation, and/or air conditioning (HVAC) systems often comprise a furnace for heating and/or otherwise conditioning interior spaces. Some HVAC systems comprise furnaces with baffles configured to redirect airflow into contact with heat exchangers. In some cases, baffles are placed in a heat exchanger compartment to reduce primary tube temperatures and increase the life expectancy of such tubes. In some furnaces, there may be a trade-off between reducing the tube temperatures, increasing air velocities, and increasing pressure drop, and thus increasing power consumption of a circulation fan blower motor. As tube temperatures decrease, external air velocities may increase, pressure drops may increase, power consumption may increase, and furnace fan efficiency may decrease.